In spite of extensive cytologic examinations in Alameda County, California there are still about 75 invasive cervical cancers and about 30 cervical cancer deaths each year. The circumstances of diagnosis are being investigated for the 373 invasive cervical cancers diagnosed in Alameda County in the years 1971-75. From hospital records it was found that 27 percent of these patients had negative cytology in recent years with 75 percent within 2 years. No information was available in the hospital records for over half the cases. Complete cytologic histories will be sought from attending physicians. Permission will be sought to have all negative cytology slides preceding diagnosis of invasive disease submitted to an independent cytopathologist for review. If the high frequency of negative cytology preceding the diagnosis of invasive cervical cancer is confirmed this would indicate that some women are apparently not able to maintain an in situ phase of cervical cancer.